Drafting mechanism



April 30, 1968 R. K. BUTLER DRAFTING MECHANISM Filed Jan. 19, 1.965

2 Sheets-Sheet 1 INVENTOR I'fw Mm VVVJ-ef@ l ATTORNEYS.

April 30, 1968 R. K. BUTLER 3,380,126

DRAFTIG MECHANISM Filed Jan. 19, 1965 2 Sheets-Sheet 2 INVENTOR RICHARD K. BUTLER ATTORNEYS.'

United States Patent Oilice 3,380,126 Patented Apr. 30, 1968 3,380,126 DRAFTING MECHANISM Richard K. Butler, Whitman, Mass., assignor to Machinecraft, Whitman, Mass., a corporation of Massachusetts Filed Jan. 19, 1965, Ser. No. 426,600 13 Claims. (Cl. lil-267) This invention relates to a drafting mechanism and esspecially to a top roll assembly for a drafting mechanism in a textile spinning machine. Most particularly the present invention relates to a top roll assembly for a drafting mechanism in a textile spinning machine which top roll assembly includes three top rolls, a front roll, a middle roll and a back roll.

Drafting mechanisms normally comprise a series of spaced apart sets of rolls made of what are commonly designated as bottom rolls and top rolls. Bottom rolls are generally driven by suitable drive mechanisms to cause them to rotate at progressively more rapid rates as viewed from front to back. The top rolls are pressed into engagement with the corresponding bottom rolls and are held there by a suitable mechanism forming part of the top roll assembly. Fibers are caused to pass between the top and bottom rolls and due to the speed differential from front roll to back roll, the fibers are drawn or drafted to greatly elongate them prior to spinning.

A number of problems have been noted in connection with top roll assemblies heretofore employed. For example, the top rolls are often biased by leaf springs into engagement with their corresponding bottom rolls. The leaf springs are generally mounted on a suitable base member forming part of the top roll assembly. As the top rolls are spaced different distances from the base member of the top roll assembly the left springs biasing the different top rolls are generally of different lengths. This gives a varying pressure characteristic between the front top roll and the bottom top roll on the one hand and, for example, the back top roll and the back bottom roll on the other. This is especially true with respect to the problem of wear. If the front top roll wears a predetermined amount the spring will deect an added distance equal to the amount of wear which deflection will reduce the amount of force applied by the left spring to the top roll by a given amount. The same amount of wear on a back roll will result in a far larger amount of reduction in biasing force due to the fact that the back roll spring is normally shorter than the front roll spring. While this can be reduced by elongating the entire top roll assembly, such elongation has serious problems of its own and is not an altogether satisfactory solution.

Other problems have manifested themselves in top roll assemblies. For example, the usual top roll assembly comprises a shaft on which two rubber rollers are fixed in spaced apart relation on the two ends thereof with a sleeve or spacer disposed between the two rollers in surrounding relation with the shaft. Commonly, a top roll is held by the spacer to permit the remainder of the top roll, that is the two rollers and the shaft to which they are afi'ixed to rotate. The two rollers normally engage similar bottom rollers which, as previously noted, are driven by a suitable driving mechanism. One of the problems which has manifested itself with this arrangement is that the two rollers in the top roll assembly are often not exerting substantially identical forces against their corresponding rollers in the bottom roll whereby to give different drafting characteristics. The present invention describes a new construction for overcoming this maldistribution of force.

Still another problem which has plagued the spinning industry with respect to top roll assemblies is that it has been common heretofore to employ what are known as aprons in connection with an intermediate roll in a top and bottom roll assembly. An apron is in effect an endless belt which serves to distribute the drafting force on the fibers over a longer distance and hence avoid problems ar1sing from the short application of very large drafting forces. However, the apron secured to the top and bottom rollers must be inproper alignment with respect to the front and back rolls of the drafting mechanism. The problem of effecting such alignment has been a troublesome one over the years and the present invention is directed to a simple solution therefor.

Still another problem which has manifested itself in connection with drafting mechanisms is that the drafting mechanism must be taken down from time to time for cleaning, repair or other maintenance. Heretofore it has been diflicult to conveniently position the top roll assembly during such shutdown.

To overcome the above and other problems, the main object of the present invention is to provide a new and improved top roll assembly for a drafting mechanism for a spinning machine.

Another object of the present invention is to provide a new and improved means for holding the top rolls in a drafting mechanism against the corresponding bottom rolls therein so that the pressure exerted by the top rolls is controllable and exhibits similar characteristics during wear.

Yet a further object of the present invention is the provision of a new and improved means for holding top rolls in a top roll assembly so that the two rollers on each of said top rolls exert substantially the same amount of force against their corresponding bottom rollers.

Yet another object of the present invention is the provision of a new and improved means for holding front and back rolls on a top roll assembly whereby to permit the even distribution of forces between the two rollers on said front and back rolls.

Still a further object of the present invention is the provision of a new and improved means for mounting an intermediate roll in a top roll assembly which means pro- Vides for the equal distribution of forces between the two rollers of said intermediate roll and, further, for the easy adjustment of and proper alignment of aprons associated with said top roll.

Still another object of the present invention is the provision of a new and improved means for releasably pressing the top rolls of a top roll assembly against their corresponding bottom rolls.

Still a further object of the present invention is the provision of a new and improved means for releasably holding a top roll assembly in a convenient non-operating position on the drafting mechanism.

The above and other objects, characteristics and features of the present invention will be more fully understood from the following description taken in connection with the accompanying illustrative drawings.

In the drawings:

FIG. 1 is a View partly in vertical section and partly in elevation showing the top roll assembly embodying the present invention;

FIG. 2 is a rear elevational view; -r

FIG. 3 is a fragmentary front elevational view of the middle roll and means for mounting same on its spring arm; and

FIG. 4 is a perspective view of a portion of the spring arm for the middle roll and the middle roll mounting block associated therewith.

Referring now to the drawing in detail, the top roll assembly embodying the present invention is generally designated by the reference numeral 10. The top roll assembly 10 includes a base member, here shown in the form of a square tube 12, a front roll 14, a middle roll 16, a back roll 18, and spring arms for holding said three rolls, which spring arms are designated by the reference numerals 20, 22 and 24. Also included is a means 26 for attaching the top roll assembly to a saddle block 28 so that the top rolls will engage bottom rolls 39, 32 and 34, respectively.

The spling arm 2G for holding the front roll 14 includes a long horizontally extending portion 36 having an aperture 38 near the right-hand end thereof, an angular extending portion 4G of short extent, a second or front horizontal portion 42 and a turned down front end 44. The spring arm 20 is secured to the interior of square tube base 12 by means of a bolt 46 whose shank 48 passes through the aperture 50 in the top of square tube 12., which aperture S is of larger extent than the bolt shank 48, and through the aperture 38 in the rear portion of the spring arm and is threadedly secured to a nut 52. By providing for clearance between the shank 48 and the aperture S0, forward and rearward adjustment of the spring arm 20 may be effected by loosening the nut and bolt 46-52 and then sliding the spring arm 2G together with the nut and bolt 46-52 back and forth to the extent that the aperture 50 will permit such sliding. A washer 53 is interposed between spring arm 20 and the top interior surface of base 12 to facilitate slippage therebe* tween. It will be obvious that a like adjustment could be obtained if tube aperture 50 snugly received bolt shank 48 and spring arm aperture 38 received bolt shank 48 with substantial clearance. The front roll 14 is positioned on the spring arm 2t) between the vertically down turned portion 44 of the spring arm and a small angle 54 secured to the horizontal portion 42 of spring arm 20 as by a rivet 55. Rivet 55 also secures a spring clip 56 to spring arm 20 which clip cooperates with downturned portion 44 to releasably hold the spacer 58 on the front roll 14 therebetween. The holding of the spacer is with a little clearance, as can be seen from FIG. l and the top of the spacer abuts against a protuberance here shown as a buttom 60 secured to (or integral with) the undersurface of the horizontal portion 42 of spring arm 20, which button serves as a pivot to permit the spacer to rock in a vertical plane so as to evenly distribute pressure force to its two rollers disposed on opposite sides of the spacer 58. One of the rollers is shown in the drawing and is designated by the reference numeral 62.

It will be seen that a toproll 14 may be readily removed and replaced by merely grasping the front roll and pushing it outwardly through the space 64 between the downturned end portion 44 of spring arm 20 and the spring clip 56 which downward movement will cause the spring clip 56 to flex rightwardly as viewed in FIG. l and thereby permit the passage of the top roller. The insertion of a new top roll can be readily edected in a similar fashion.

The back roll 18 is held on its spring arm 24 in a substantially identical fashion to front roll 14. That is to say the spacer 66 of the back roll is held between a downwardly extending front end portion 68 of spring arm 24 and a spring clip 70 which is secured to the spring arm 24 together with an angle element 72 by a rivet 74. Moreover, the spacer 66 of the back roll is in engagement with a pivot-like button 76 secured to the undersurface of the spring arm 24 which button 76 functions as .a pivot in exactly the same manner as the button 60 to give equal distribution of force to the two rollers of the back roll 1S.

It will be noted that the back roll 18 is spaced from the rectangular tubular base 12 of the top roll assembly 10 by a much shorter distance than is the front roll 14. If the spring arms 20 and 24 differ in length by substantially the same amount as the difference in spacing between the front roll and the base on the one hand and the back roll and the base on the other, there would be a serious difference in characteristic of the spring arms 26 and 24 during wear of the front and back rolls 14 and 18, respectively. That is to say, with the front spring arm 20 approximately twice as long as the rear spring arm 24, for a given amount of wear of the front top roll 14, the relief of tension in the spring arm 20 would be much less than the relief of tension in spring arm 24 resulting from the same amount of wear of the back top roll 18. Since the distribution of force between all of the top rolls is a vital consideration in drafting equipment, it is desirable to eliminate this potential problem.

In accordance with the present invention the problem is eliminated by lengthening spring arm 24 without elongating the entire top roll assembly by means of turning the right-hand or rear end of the spring 24, that is the end 78, 180 degrees whereby to render spring arm 24 much longer while still 4maintaining it compact. The upper reach of the spring arm 24, herein designated by the reference numeral 80, is close to and parallel to the inside surface of the top of base 12 and is provided with an aperture 82 which permits the shank 84 of a bolt 86 to pass therethrough for securing the spring arm 24 to the base 12. The shank 84 of the bolt 86 also passes through an aperture 88 in the base 12 with clearance whereby to enable the spring arm 24 together with the bolt 86 to be moved back and forth to adjust the position of spring arm 24 with respect to the base 12 within the limits permitted by the aperture 88. As shown, a washer 89 is interposed between -portion of spring arm 24 and the interior of base 12 to facilitate sliding therebetween.

Also secured to the base 12 interiorly thereof by the bolt 86 is the spring arm 22 for the middle roll 16. This securement is effected by means of a washer or spacer 90 which extends between the spring armf24 and the spring arm 22 and a nut 92 threadedly secured to the bottom of the threaded shank 84 of the bolt 86. It will be seen that the threaded shank 84 passes through/an aperture 94 in the right-hand end of spring arm 22y with substantial clearance whereby to permit adjustment forward and backward of the spring arm 22 relative to the base 12. It will further be seen that when the bolt S6 is loosened, notwithstanding the fact that both spring arms 22 and 24 are fixed to base 12 lby the same nut and bolt, the two spring arms 22 and 24 may be independently adjustably positioned relative to base 12 since the means for adjusting them are independent of one another. That is to say, if the spring arm 32 is moved back and forth there will be no movement of the nut and bolt 86-92 and hence no movement of the spring arm 24, due to the clearance provided by the aperture 94. Moreover, if it is desired to adjust spring arm 24 this can be accomplished by moving the `bolt 86 and hence the spring arm 24 which movement will not be imparted to the spring arm 22 -due to the clearance provided between the shank S4 of bolt 86 and the aperture 94. Further, as already noted, the adjustment of spring arm 20 is completely independent of the adjustment of spring arms 22 and 24. Thus it will be seen that all three'spring arms are easily adjusted by means of readily accessible bolts 46 and 86 without interfering with the location of the other spring arms. It will be obvious that a similar independent adjustment can be achieved by proportioning aperture 82 to receive bolt shank 84 with substantial clearance and aperture 94 to receive bolt shank 84 with little clearance, or alternatively, to have both apertures 82 and 94 receive bolt shank 84 with substantial clearance.

The middle roll 16 is not held on its associated spring arm 22 in the same manner as the front and back rolls 14 and 18 are held on their associated spring arms. This is due to the fact that associated with the middle roll 16 are aprons 96 and 98 which are endless belts. The upper apron 96 passes around the rollers associated with the top roll 16 and around an upper tensor 100. The bottom apron 98 passes around the bottom roll 32 and a second or lower tensor 102. Due to the inclusion of the aprons, the tensors and the means for holding the tensors in position, it is found desirable to use a special mounting means for the middle roll which insures against rotation of the middle roll spacer. To mount the middle roll 16 on its spring arm 22 in order to yield a rockable mounting which will permit equal distribution of force between both rollers of the middle top roll 16 and their associated bottom rollers, and yet hold the spacer securely against rotation, a mounting block 104 is employed. The mounting block 104 is provided with an aperture 106 adapted to receive the spacer 108 of the middle roll 16. The mounting block 104 is provided with a slot 110 which communicates with the aperture 106 and with the outside whereby to form the mounting block 104 into a split hub. Mounting block 104 is somewhat flexible or resilient, being made preferably of a metal such as steel, although other materials may be employed. A threaded stud 112 in threaded engagement with the mounting block is provided to open and close the slot 110 to thereby relieve and apply a clamping pressure by the mounting block 104 on the spacer 108. In this way the spacer and hence the entire middle roll 16 is held in the mounting block 104 while the rollers 135 and 137 are free to rotate together with their shaft 139. The mounting block 104 is secured to a dome-shaped portion 114 of the spring 22 by means of a securing element 11-6 having a head 118 of greater extent than an aperture 120 in the domeshaped portion 114 of spring arm 22 and a shank 122 of lesser extent than said aperture 120, said shank being secured to the mounting block 104 as by a threaded connection or a pressed t. With the arrangement as described the mounting block 104 engages the dome-shaped portion 114 of spring arm 22 but is -free to move slightly relative thereto due to the clearance between the shank 122 and the aperture 120. As may lbest be viewed in FIGS. 3 and 4, the mounting block 104 engages the dome-shaped portion 114 along two lines of engagement which lines are designated by the reference numerals 124 and 126. The mounting block 104 is therefore provided with two lines to pivot about, either the line 124 or the line 126 to enable it to redistribute inequality of pressure between its two rollers.

It will be seen from FIGS. l and 4 that the clamping screw or stud 112 is accessible from above the top roll assembly by a screwdriver or Allen wrench or the like -by the provision in spring arm of an aperture 128 and in spring arm 22 of an aperture 130 -both of which are in alignment with the head of the threaded stud 112. Thus to adjust the clamping pressure of the mounting block 104 on the spacer 108 of the middle roll 16, all that need be done is to insert the appropriate tool through the aligned apertures 128 and 130 into engagement with the head of the stud 112 to loosen the stud and thereby permit adjustment. Thereafter the mounting block can be tightened to reclamp the spacer 108 in the aperture 106.

As previously noted there are aprons 96 and 98 associated with the middle top roll 1-6 and the middle bottom roll 32 to distribute the drawing or drafting force exerted by said middle rolls on the fiber moving therethrough. These aprons 96 and 98 pass around their associated top and bottom middle rolls 16 and 32, respectively, and around the leading or forward edges of their respective tensors 100` and 102. The tensors 100 and 102 are merely long flat bars which are held by two spaced apart -brackets 132 and 134 which in turn are fixed to the spacer 108 of center roll 16 adjacent the two top center rollers 135 and 137, respectively. The tensors extend outwardly of the brackets 132 and 134 on both sides and terminate in substantially the same vertical planes as the ends of the top and bottom rolls 16 and 32. Each of the brackets 132 and 134 is provided with vertically spaced notches 136 and 138 in horizontal alignment. Thus it will be seen that not only does the top roll 16 support its own apron 96 but its supports the apron 98 associated with the bottom middle roll 32.

The above described structure for mounting the aprons on the middle roll greatly facilitates the adjustment of position of the aprons relative to the front and back rolls. Such adjustment may be readily effected with the present arrangement by passing an appropriate tool through the aligned apertures 128 and 130 in the spring arms 20 and 22, respectively, in order to engage the threaded stud 112 and turn that stud to loosen the clamping force of the mounting :block 104 on the spacer 108 of the middle roll 16. With the clamping force relieved the spacer may be turned relative to the mounting block whereby to turn the notched brackets 132 supporting the tensors and 102 to thereby shift the tensors and hence relocate the throat of the path defined by the confronting surfaces of the aprons 96 and 98 and to redirect that path. Once proper location of the tensors is achieved, the tool extending through the apertures 128 and 130 may be manipulated to once again tighten the mounting block 104 to clampingly hold the spacer 108 and hence the tensor mounting brackets 132 and 134 in locked position.

Because of the construction of the middle roll it will be seen that when it is desired to move the top roll assembly 10 out of working relation with the bottom rolls, the top roll assembly cannot merely be moved upwardly, such as by pivoting, for such upward pivotal movement would ybe interfered with by the interconnection between the top roll assembly 10 and the 'bottom rolls through the apron 98. Accordingly, prior to movement of the top roll assembly 10 away from the bottom rolls, there must be movement of such a nature as to permit the removal of the lower apron 98 from the apparatus- A study of FIG. 1 will illustrate that this is :best achieved yby moving the top roll assembly rearwardly of the bottom rolls a short distance whereby to relieve tension on the bottom apron 98 to permit its removal by sliding apron 98 in a plane perpendicular to the plane of FIG. l. In order to yield this type of connection which will enable such a rearward sliding movement, a novel means for attaching the top roll assembly 10 to the saddle block is employed. This means includes the latching arrangement 26 previously mentioned.

Referring to FIG. 1, the saddle block 28 is secured to a back bar yby providing the saddle 'block with an arcuate groove 142, a substantial extent of which is complementary to the back bar 140. The 'back Ibar is threaded as at 144 to threadedly receive a =bolt 146 having a bolt head 148 in clamping engagement with the saddle block 28. Of course, bolt 146 could pass through back bar 140 and be fastened by a nut. The saddle block is provided with an aperture 150 to permit the bolt 146 to pass therethrough with some clearance. Hence, when the bolt 146 is loosened, the saddle block may be swung or pivoted a short extent relative to the back bar 140 for reasons which will become apparent hereinafter. In order to prevent such swinging movement during normal operation a set screw 152 is provided which set screw is in threaded engagement with the saddle block and is adapted to abut against the bolt 146 to prevent swinging movement of the saddle block during normal operation. The means for gaining access to the set screw 152 will be described hereinafter.

As previously noted, in order to secure the top roll assembly 10 to the saddle block 28, a latching means 26 is provided, The latching means includes a vertically extending plate-like latch 154 which is secured to the base 12 in its depending position by means of abutments 156 on the latch 154 which engage the interior of the tubular base 12, and a securing pin 158 immediately exterior of said 'base tube 12. The latch 154 is provided `with a forward notch 160 and a rear notch 162. The depending latch 154 is adapted to t into a slot 164 in the saddle 4block which slot has a relatively shallow rear portion 166 and a shaped and deeper forward portion 168, the latter of which is adapted to receive the latch 154, when the top roll assembly is in operative position. The rear portion 166 of the slot 164 provides, among other things, access to set screw 152. Rotatably mounted on the saddle block and extending transversely thereof is a shaft 169 having an end portion thereof extending outwardly of the saddle block in order to be secured to a crank 170 for rotating the shaft. The central portion of the shaft, that is the portion which extends `through the deep portion 168 of saddle block slot 164, is machined to `provide an eccentric 172 which is adapted to tit into this forward slot 160 on latch 154-. When the crank 171i is in a raised position (not shown but substantially 180` degrees counterclockwise from the position shown in FIG. l) the eccentric is raised and is out of engagement with the bottom of the forward notch 160 and in engagement with the top thereof. in that raised position, there is no downward force other than gravity being applied to the top roll assembly 19. Accordingly the top roll assembly is free to be moved rearwardly until the right-hand edge of latch 154 engages the right-hand end of the deep portion 168 of slot 164 in which position the front edge of the latch is clear of the eccentric 172. In the rearwardly moved position of the assembly :the lower tensor 182, which is carried by the top roll assembly, is so positioned that there is little or no tension on the lower apron 98 and hence the lower apron is free for removal from its position around tensr 102 and the middle bottom roll 32. With the apron 98 removed and latch 154 clear of eccentric 172, the top roll assem'bly 10 is free to be moved upwardly to disengage it from the saddle block. If desired the top roll assembly can `be held in a non-operating position on the saddle block slightly more than 90 degrees clockwise from the position shown in FIG. l by hooking the rear slot 162 of the latch 154 about a standup pin 174 extending across slot portion 166 in the saddle block 28. This provides a convenient means for holding the top roll assembly in inoperative condition.

When it is desired to reposition the top roll assembly in `operative relation with the bottom rolls, the top roll assembly is moved upwardly to unhook the latch from the standup pin 174 and then `the top roll assembly 10 is placed in horizontal orientation with the latch 154 aligned with the deep portion 168 of saddle block slot 164 and the forward edge of latch 154 rearward of eccentric 172. With this alignment achieved, the top roll assembly 10 can ybe moved downwardly until the bottom surface of the rectangular tube base 12 engages the upper surface of the saddle 'block 28. Then the top roll assembly may 'be moved forwardly to bring the forward latch slot 160 into surrounding relation with the eccentric 172 which eccentric is in its raised position (not shown). The forward movement continues until apertures 176 in the bottom surface of the rectangular tube base 12 receive bevelled locating pins 178 which extend a slight distance upward of the top surface of the saddle block 28. When the apertures 176 receive the tops of the locating pins 178, the top roll assembly is properly positioned with respect to the saddle block and the operator may then move the crank 170 clockwise to the position shown in FIG. 1 whereby to move the eccentric out of engagement with the upper surface of notch 160 and into engagement with the 'bottom surface of notch 160 to thereby press the top roll assembly down and thereby bring the top rolls 14, 16 and 18 into engagement with the bottom rolls 30, 32 and 34, respectively.

Once in position, if it is noted that there is any maladjustment of location of the top rolls with respect to one another or with respect to the bottom rolls, adjustment of these positions can be accomplished by manipulation of the bolts 46 and 86 as previously noted. Moreover, there may Ibe misalignment of the `passage defined by the aprons 96 and 98 with either the front rolls or the back rolls, especially with the front rolls. This misalignment may be corrected in the manner previously described.

If it is noted that the pressure 'between the top rolls and the bottom rolls is not properly adjusted, a gross adjustment may be made by once again removing the top roll assembly 1t) from its operative lposition in the saddle block and then adjusting the position of the saddle block relative to the back bar 140 by turning the set screw 152 to unlock bolt 146, and then loosening bolt 146 to free the saddle block for a turning adjustment relative to the back bar. After the adjustment has been made, bolt 146 is retightened to clamp the saddle Iblock on the back bar and the set screw 152, access to which is gained through narrow slot portion 166 of saddle `block slot 164, is tightened against bolt 146 to relock the saddle block in the newly adjusted position. Then the top roll assembly 10 may 'be repositioned on the saddle block and clamped thereon `by operation of eccentric 172.

Thus it will be seen that my novel top roll assembly yields many forms of adjustment of various components, each of which adjustment may be effected independently of other adjustments. Further, with the simplified latch arrangement including latch 154 and eccentric 172, the placement of the top roll assembly on the saddle block and its removal therefrom can be effected quickly and easily. In addition, by mounting all of the spring arms within the interior of square base 12, a neat, compact and easily handled assembly results.

It will be understood that while the various features of the present invention have been disclosed with respect to a top roll assembly having a front roll, a middle roll and a back roll, various features of the present invention may be employed with respect to other types of top roll assemblies. Thus, for example, more than one roll intermediate the front and back may be employed without departing from the spirit of the invention.

While I have herein shown and described the preferred form of the invention and have suggested modifications therein, other changes and modications may be made therein within the scope of the' appended claims without departing from the spirit and scope of the invention.

What I claim is:

1. A top roll assembly for a drafting mechanism, comprising a tubular base member (in the form of a tube) having a rectangular cross-section, a first spring arm for connecting a front roll to said tubular base member, a second spring arm for connecting a back roll to said tubular base member, a third spring arm for connecting an intermediate roll to said tubular base member, said tirst and third spring arms being substantially unidirectionally extending members; said second spring arm having a C-shaped intermediate portion, an upper end p0rtion extending away from said tubular base member in a direction opposite to the direction of said first and third spring arms and a lower end portion extending away from said C-shaped intermediate portion in the same direction as said rst and third spring arms, means for connecting said first spring arm to the upper surface of said tubular base member in close confronting relation therewith, and means for connecting said second and third spring arms to said tubular base member rearwardly of said rst spring arm comprising a securing element passing through the top surface of said tubular base member, said upper end portion of said second spring arm and said third spring arm.

2. The top roll assembly of claim 1, further comprising means for independently adjusting the position of said second and third spring arms relative to said tubular base member.

3. A top roll assembly for a drafting mechanism, comprising a tubular base member (in the form of a tube) having a top, bottom and two sides arranged in a rectangular cross-section, a rst spring armk for connecting a front roll to said tubular base member, a secondspring arm for connecting a back roll to said tubularbase member, a third spring arm for connecting an intermediate roll to said tubular base member, said rst and third spring arms being substantially unidirectionally extending members and extending away from said tubular base member in the same direction; said second spring arm having a C- shaped intermediate portion, an upper end portion extending away from said tubular base member in a direction opposite to the direction of said rst and third spring arms and a lower end portion extending away from said C-shaped intermediate portion in the same direction as said first and third spring arm extend away from said tubular base member; said top of said tubular base member and said rst spring arm having aligned apertures therein, a bolt having a head above said tube and a threaded shank passing through said aligned apertures, a nut threadedly connected to said shank for securing said first spring arm to said top of said tubular base member in close confronting relation therewith, at least one of said aligned apertures being substantially larger than said bolt shank for permitting the adjustable positioning of said first spring arm relative to said tubular base member, said top of said tubular base member having a second aperture spaced from said first mentioned aperture in a direction opposite to the direction of said first spring arm, the upper end portion of said second spring arm and said third spring arm each having apertures in alignment with said second aperture in said tubular base member, another bolt having a head above said tubular base member and a shank extending through said second aperture in said tubular base member and said aligned apertures in said second and third spring arms, another nut threadedly secured to the free end of said other bolt for releasably securing said second and third spring arms to said tubular base member, at least two of said second aperture and said apertures in said second and third spring arms receiving the shank of said other bolt with substantial clearance, whereby to enable the independent adjustment of said second and third spring arms relative to said tubular base member.

4. In a drafting mechanism, a top roll assembly comprising a top roll including a pair of rotatable rollers and a stationary spacer therebetween, a base, and a spring arm operatively connected at one end to said stationary spacer and operatively connected at its other end to said base; a bottom roll companion to said top roll; a saddle block stationary relative to said bottom roll and disposed rearwardly thereof, said saddle block having an upper surface with a slot therein extending in the direction toward said bottom roll, a transversely extending rotatable shaft on said saddle block, an eccentric on said shaft disposed within said slot and being movable between a low position and a high position, and a plate-like latch depending from said base and disposable in said slot, said latch having a notch therein proportioned to receive said eccentric therewithin, said latch and eccentric being proportioned and positioned so that when said eccentric is received in said notch with said base resting on said upper surface of said saddle block and said eccentric is in its low position, said base is clamped against said upper surface of said saddle block and said top roll is pressed into operative relation with said bottom roll.

5. In the drafting mechanism of claim 4, wherein said slot is of greater longitudinal extent than said latch, said notch is in the front edge of said latch, and said notch is brought into and out of surrounding relation with said eccentric by moving said latch relative to said saddle block in the forward direction and in the rearward direction, respectively.

6. In the drafting mechanism of claim 4, said slot in said saddle block extending to the rear edge thereof, a stand-up pin extending across said slot adjacent the rear end thereof, said latch having a notch in the rear edge thereof adapted to receive said stand-up pin whereby to enable said top roll assembly to be hooked onto said stand-up pin to releasably hold said top roll assembly in a non-operating position substantially perpendicular to the position in which it is clamped by said eccentric.

7. In a drafting mechanism of claim 5, further comprising a pair of vertically spaced apart horizontally extending tensors, means connected to said top roll spacer for supporting said tensors, a top apron extending around said top roll and said upper tensor, a bottom apron extending around said bottom roll and the lower of said tensors.

8. In a drafting mechanism of claim 4, wherein said one end of said spring arm is curved about its longitudinal axis, and the operative connection between said one end of said spring arm and said stationary spacer comprises, a mounting block, means connecting said mounting block to said one end of said spring arm including a securing element having a head disposed on the upper surface of said spring arm and a shank passing through said spring arm with clearance and being fixed to said mounting block, whereby to permit a rocking of said mounting block about axes parallel to the longitudinal axis of said spring arm, said mounting block having a passage therein for receiving said spacer and a slot communicating with said passage and extending to the exterior of said mounting block, a threaded securing element extending across said mounting block slot and being threadedly connected to said mounting block for flexing same to clamp and release said spacer in said mounting block passage.

9. In the drafting mechanism of claim 8, further cornprising a pair of spaced apart vertically extending mounting brackets each having horizontally aligned vertically spaced notches therein, an upper tensor mounted in said upper aligned notches in said mounting brackets and a lower tensor mounted in the lower aligned notches in said mounting brackets, a top apron extending around said top roll and said upper tensor, a bottom apron extending around said bottom roll and the lower of said tensors.

10. In the drafting mechanism of claim 8, further comprising a second top roll, a second spring arm extending above said first spring arm and operatively connected at one end to said base and at its other end to said second top roll, said rst and second spring arms each having an aperture therein in alignment with said threaded securing element for providing access thereto from above said second spring arm.

11. In a drafting mechanism, a back bar of circular cross section, and a saddle block mounted thereon, said saddle block having an arcuate groove therein for receiving said back bar, said back bar and said saddle block having aligned openings, means for connecting said saddle block to said back bar including a bolt in said openings, the opening in said saddle block being of larger crosssection than said bolt to permit relative movement between said saddle block and said back bar when said bolt is loose, said saddle block having a groove in the upper surface thereof, said groove being aligned with said bolt, said saddle block further having a threaded passage extending from said saddle block groove to said aligned saddle block opening, and a set screw threadedly mounted in said threaded passage and being engageable at its lower end with said bolt for limiting relative movement between said saddle block and said back bar, the upper end of said set screw being accessible through said groove in the upper surface of said saddle block.

12. A drafting mechanism comprising a back bar, a saddle block, means for adjustably positioning said saddle block on said back bar, a top roll assembly, means for releasably latching said top roll assembly on said saddle block; said top roll assembly comprising a base, a front roll, a back roll and an intermediate roll, first and second substantially forwardly extending spring arms extending respectively from said base to said front and intermediate rolls, a third spring arm having a rearwardly extending end portion, a C-shaped intermediate portion and a forwardly extending end portion, Said three spring arms being substantially of equal length, means for mounting said spring arms on said base for independent adjustment relative thereto, and means for rockingly connecting said rolls to their respective spring arms for rocking movement about forwardly extendingv axes.

13. A top roll assembly for a drafting mechanism, comprising a base member, a front roll, a back roll, means for connecting said front roll to said base member comprising a rst leaf spring secured to said base member at one end and extending substantially unidirectionally away 11 therefrom and being operatively connected to said front roll at its other end, means for connecting said back roll to said base member comprising a second leaf spring secured to said base member at one end and extending away from the point of securement rst in one direction and then having a C-shaped bend therein and then extending in a direction opposite to said given direction and being operatively connected to said back roll at its other end, said first and second leaf springs being of substantially the same length between their points of securement to said base and their points of operative connection with their associated roll, said operative connection between one of said front and back rolls and its associated leaf spring comprising a transversely extending end portion of said leaf spring and a spring clip operatively connected to said leaf spring rearwardly of said transverse end portion, and a protuberance on the surface of said leaf spring facing the direction toward which said transverse portion extends, said protuberance being engageable with said roll to serve as a pivot therefor.

References Cited UNITED STATES PATENTS 2,675,586 4/ 1954 Hohloch 19-281 X 2,834,995 5/ 1958 Calvert et a1. 19--277 2,870,487 1/ 1959 Dausch et al. 19-281 X 3,091,814 6/1963 Huber et a1. 19-281 3,278,994 10/ 1966 Stahlecker et al. 19--295 XR FOREIGN PATENTS 1,235,017 5/ 1960 France.

898,803 6/ 1962 Great Britain.

DORSEY NEWTON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,380 ,lZ6 April 30 1968 Richard K. Butler It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below: i

Column l, line 43, "left" should read leaf Column 3, line 37, "buttom" should read button Column 8, line: 34 and 61, cancel "(in the form of a tube)", each occurrence.

Signed and sealed this 28th day of October 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents 

1. A TOP ROLL ASSEMBLY FOR A DRAFTING MECHANISM, COMPRISING A TUBULAR BASE MEMBER (IN THE FORM OF A TUBE) HAVING A RECTANGULAR CROSS-SECTION, A FIRST SPRING ARM FOR CONNECTING A FRONT ROLL TO SAID TUBULAR BASE MEMBER, A SECOND SPRING ARM FOR CONNECTING A BACK ROLL TO SAID TUBULAR BASE MEMBER, A THIRD SPRING ARM FOR CONNECTING AN INTERMEDIATE ROLL TO SAID TUBULAR BASE MEMBER, SAID FIRST AND THIRD SPRING ARMS BEING SUBSTANTIALLY UNIDIRECTIONALLY EXTENDING MEMBERS; SAID SECOND SPRING ARM HAVING A C-SHAPED INTERMEDIATE PORTION, AN UPPER END PORTION EXTENDING AWAY FROM SAID TUBULAR BASE MEMBER IN A DIRECTION OPPOSITE TO THE DIRECTION OF SAID FIRST AND THIRD SPRING ARMS AND A LOWER END PORTION EXTENDING AWAY 